1. Field
The present disclosure relates to sample analysis methods and apparatuses that analyze a sample by using a microfluidic apparatus including a valve operated with external energy, and to methods of dynamically opening and closing a valve.
2. Description of the Related Art
Most deaths relating to malignant tumors are caused by metastasis of the tumor from an initial position where a tumor occurs, to a tissue and an organ which are separated from the initial position. Therefore, early detection of tumor metastasis is an important factor for increasing a survival probability of a cancer patient, and early tumor detection and monitoring of tumor growth are considered very important factors in successfully treating a cancer patient. It is known that circulating tumor cells (CTCs) are detected from a patient before a tumor is detected for the first time. Therefore, CTCs play an important role in early detection and prediction of cancer. Also, since cancer is generally metastasized through blood, a CTC may be an indicator for diagnosing whether cancer is metastasized.
Sample analysis, which typically involves separating a target cell such as a CTC, a cancer cell, or a cancer stem cell from a sample, may use a disk-shaped microfluidic apparatus including a microfluidic structure which causes a flow of a sample due to a centrifugal force. The microfluidic apparatus includes a valve used to control a flow of a sample. The valve operates with energy supplied from the an external source. In order to operate the valve, a sample analysis process stops rotation of the microfluidic apparatus, supplies energy to the valve to melt a valve material, and again rotates the microfluidic apparatus. However, samples centrifuged from a plurality of layers are again mixed in a process of operating the valve, causing degradation in the reliability of analysis. Also, the melted valve material is solidified in a process of again rotating the microfluidic apparatus, and thus the valve cannot operate or operates unstably.